Tideway anchor

ABSTRACT

An anchor for use in a tideway, in which one of a pair of mating components is fixed to the sea bed and the other is held in contact with it by means actuated by reciprocal movement in the plane of the tide of a member which offers resistance to the flow. This allows the components to be separated at the tidal null points. The components may also be sealed together by the reciprocal movement.

BACKGROUND OF THE INVENTION

The lateral force of tidal flow on objects positioned on the sea bed is considerable, especially if it is equipment for extracting energy from the tide. The following improvement is particularly designed for use with my tidal energy invention, disclosed in W02007086037, but of course has other applications also. It uses a plug and socket type of anchoring, as can be found in the disclosure of EP0045613 (A1). The latter disclosure is for semi-permanent anchoring, but for use with equipment for tidal energy, it is necessary for the plug to which the equipment is attached to be able to be withdrawn at fairly frequent intervals from its socket for maintenance of the equipment.

BRIEF SUMMARY OF THE INVENTION

If friction alone is relied upon to keep both components of the anchor together when the tidal force is acting to separate them, the socket in the sea bed needs to be deep. This depth can be greatly decreased if plug and socket are positively locked together when the tide is flowing. This of course has to be combined with absolutely reliable means of unlocking them during the tidal null period, so that the plug and whatever is attached to it can be removed for maintenance purposes at that time. This invention achieves both these objectives through a locking mechanism which is actuated by reversal in the direction of the tidal flow.

DESCRIPTION OF THE DRAWING

The FIGURE is a section of an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the FIGURE, 1 is a plug to which whatever is desired to be anchored in the tidal stream is attached, and 2 is a socket in the sea bed into which plug 1 fits. 7 is a shaft which pivots on axle 8, journalled in trunnion 9 attached to the top of plug 1, so that it can move in an arc about its axis in the plane of the tidal stream and under the force of the stream. Such a shaft, for example, could be the drive shaft shown in my tidal turbine invention or an extension of it. 10 is a master hydraulic cylinder, whose piston rod is attached to and movable by the lower end of shaft 7. Master cylinder 10 is connected by hoses 11, 11 to a pair of slave cylinders, 12, 12, which are rigidly fixed to the inside wall of plug 1. 13, 13 are rollers on the end of the piston rods of slave cylinders 12, 12; and 14, 14 are a pair of locking bars which are shaped to slide into and out of slots 15, 15, cut in the walls of plug 1 and also into and out of slots 16, 16, cut in the walls of socket 2. 17, 17 are angled slots in locking bars 14 within which rollers 13, 13 can move to cause lateral movement of these bars. The upper surfaces of bars 14, 14 are chamfered, so that when they encounter rollers 18, 18, attached to the upper surfaces of slots 15, 15, they cause plug 1 to be forced downwards within socket 2, compressing flexible seal 19 between them at the lower end of plug 1. This is to enable a water pump (not shown) within plug 1, to force water efficiently through orifice 20 in plug 1, tube 21 and conduit 22 to where its kinetic energy can be used, when the tide is running. Plug 1 can of course incorporate an electrical generator instead of a pump, in which case seal 19 may not be needed.

In operation of the invention, at the tidal null point there is no lateral force on shaft 7, so that it takes up a vertical position. When the tide flows, it will bring whatever is attached to the part of shaft 7 that is above axle 8 (such as a tidal turbine) downstream with it, in the plane of the tidal stream. If necessary, this movement will also rotate plug 1 inside socket 2 so as to align slots 15 and 16 with each other. When the part of shaft 7 that is above axle 8 moves in the plane of the tidal stream and under its pressure, the part of the shaft below axle 8 will move the piston in master hydraulic cylinder 10 so as to force fluid through hoses 11 into slave cylinders 12. The pressure from this forces the piston rods in slave cylinders 12 downwards. Because rollers 13 on the end of these rods run in slots 17, and because the slave cylinders cannot move, downwards movement of rollers 13 forces bars 14 laterally into slots 16 in the wall of socket 2. Bars 14 cannot move from there as long as the tide is running, so that plug 1 and socket 2 are positively locked together throughout this period. This makes it quite impossible for the vertical component of the tidal force on anything being held by the anchor, to pull plug 1 out of socket 2 up to the limit of the constructional strength of their various parts.

At the tidal null point, because of a degree of buoyancy in the tidal turbine or whatever is attached to shaft 7, this shaft will return to the vertical position. This reverses the movement of hydraulic fluid, moving the piston rod of each slave cylinder upwards and causing the resulting movement of rollers 13 to withdraw bars 14 from slots 16 in socket 2. At this time, plug 1, with any equipment attached to it, can be freely withdrawn from socket 2 and removed for maintenance. Re-starting of the tidal flow in the reverse direction will then repeat the locking cycle. There are several other ways of putting the invention into effect within the scope of the invention. Reciprocal movement under pressure from the tidal flow could act upon the locking mechanism through directly connecting rods or cables. The locking system could be operated from a power source, such as an electrical battery, incorporated in plug 1, and actuated by a timer, because future tidal movements can be predicted with complete accuracy, or by a remote signal. 

1. An anchor for gear in a tideway of the type which consists of a pair of mating components, one of which is fixed to the sea bed, the other being removable and adapted for whatever is to be anchored to be attached to it, characterised by means for locking both components positively together during the period of tidal flow and unlocking them during the tidal change period.
 2. An anchor as in claim 1, in which the locking means also seals both components together
 3. An anchor as in claim 1 or 2, in which the locking means is actuated by reciprocating movement of a component in the tidal stream, caused by the reversal of that stream.
 4. An anchor as in claim 1 or 2, in which the locking means is actuated by timer control of a source of power incorporated in one of the anchor components.
 5. An anchor as in claim 1 or 2, in which the locking means is actuated by a remote signal to a source of power incorporated in one of the anchor components. 